This invention relates a gas generating propellant. More particularly, a mixture of guanidine nitrate and a specific oxidizer, potassium perchlorate or ammonium perchlorate, generates nitrogen, carbon dioxide and steam when ignited.
Gas generating compounds evolve a copious volume of gas when ignited. One category of gas evolving compounds utilizes a guanidine (HN.dbd.C(NH.sub.2).sub.2) based compound mixed with a sensitizer and/or oxidizer. For example, U.S. Pat. No. 2,165,263 to Holm discloses a gas generating compound containing nitroguanidine in a binder. A portion of the nitroguanidine may be replaced with guanidine nitrate (H.sub.2 NC(NH)NH.sub.2 .cndot.HNO.sub.3). Typical binders include nitrocellulose and cellulose acetate.
U.S. Pat. No. 3,719,604 to Prior et al, discloses a mixture of an oxygen liberating compound, such as potassium chlorate, and a gas evolving compound such as ammonium nitrate or guanidine nitrate.
U.S. Pat. No. 3,739,574 to Godfrey discloses a gas generator containing a mixture of guanidine nitrate and ammonium nitrate which is decomposed in the presence of a chromic oxide catalyst.
The above mixtures evolve a generous quantity of oxygen and nitrogen gases. However, the gas volume and gas temperature is inadequate for use in augmented airbags as utilized in automotive passenger restraint systems. In a first compartment of such an airbag, elevated temperature nitrogen gas is generated by ignition of a mixture of an azide-and an oxidizer. One disclosed mixture is sodium azide and potassium perchlorate. The generated nitrogen passes through a perforated plate into a second compartment containing a pressurized gas which expands on exposure to the hot nitrogen gas generated in the first compartment. In a third compartment, the gases inflate an air bag to restrain an automobile passenger.
Sodium azide is difficult to handle safely and is toxic. Assembly of the airbags must be done in a controlled environment and disposal of uninflated airbag cylinders is difficult.
Guanidine nitrate is easier to handle and not as toxic as sodium azide. The development of a guanidine nitrate based airbag component would improve the safety of manufacture and transport and lessen the environmental concerns of disposal.